1. Field of the Invention
The present invention relates to semiconductor device having a BGA structure and methods for manufacturing the semiconductor device, and more particularly to a semiconductor device having a BGA structure and the method for manufacturing the same, the semiconductor device being capable of preventing the generation of cracks in a solder ball with an impact propagated from a printed wiring board at the time of a fall impact test and at a time of a temperature cycle test, which tests are carried out in the state in which the semiconductor device is attached on the printed wiring board.
2. Description of the Related Art
Conventionally, there is available a semiconductor device in which a lead is used in the connection terminal. FIG. 1 is a sectional view showing a semiconductor device in which a lead is used as the connection terminal.
As shown in FIG. 1, in the semiconductor device 50, in which the lead is used as the connection terminal, there is provided a semiconductor chip 71, and an internal leads 73a of a plurality of connection leads 73 are arranged in parallel with the upper surface of the semiconductor chip 71 above the semiconductor chip 71. The semiconductor chip 71 and the internal leads 73a of the connection leads 73 are stuck and fixed with a sticking tape 79 comprising an insulator. Furthermore, a pad 75 formed on a central part of the upper surface of the semiconductor chip 71 and the internal leads 73a of the connection leads are electrically connected with wires 76.
The semiconductor chip 71, the sticking tape 79, the internal leads 73a of the connection leads 73, the pad 75 and the wire 76 are covered with the result that a resin sealed part 72 is formed. Furthermore, external leads 73b of the connection leads 73 are extended from the resin sealed part 72 and bent, and the tips of the external leads 73b are arranged under a lower surface of the resin sealed part 72.
In the semiconductor device 50 which is constituted in this manner, the tips of the external leads 73b are fixed and connected electrically to predetermined portions of a printed wiring board with soldering or the like, and the semiconductor device 50 is set on the printed wiring board.
In the semiconductor device 50, however, since the connection terminal is composed of the lead, it is required to prepare a solder or the like separately in advance to connect the connection terminal to the printed wiring board with the solder in the case where the connection terminal is attached on the printed wiring board. Thus, there is a disadvantage that the connection work is troublesome.
As a semiconductor device which has overcome that disadvantage, there is available a BGA (Ball Grid Array) structure. The BGA structure is constituted with a ball having a connection lead comprising solder or the like. Two kinds of semiconductor devices having the BGA structure will be explained in the forgoing description.
FIG. 2A is a perspective view showing a semiconductor device having the BGA structure disclosed in U.S. Pat. No. 5,677,566, FIG. 2B is a sectional view thereof. As shown in FIGS. 2A and 2B, in the first conventional semiconductor device having the BGA structure 110, there is provided a die pad 140 and a semiconductor chip 114 provided thereon. Furthermore, a plurality of connection leads 115 are electrically connected to the pad 118 formed on the end part of the upper surface of the semiconductor chip 114 with a wire 122. Furthermore, solder balls 128 are allowed to bond on the upper surfaces of the connection leads 115, respectively. A part of the solder ball 128 and the connection lead 115 are exposed and are covered together with the die pad 140, the semiconductor chip 114, the pad 118 and the wire 122 so that a resin sealed part 126 is formed.
In the first semiconductor device 110 having the BGA structure which is constituted in this manner, the solder balls 128 are allowed to come into contact with a predetermined positions of a printed wiring board. Then, by means of a reflow method for allowing the solder balls 128 to come into contact with predetermined positions of the printed wiring board and heating or pressing the solder ball 128 to melt, the semiconductor device is fixed to a predetermined position of the printed wiring board, and, at the same time, is electrically connected to the printed wiring board and is attached on the printed wiring board.
FIG. 3A is a perspective view showing the semiconductor device having the BGA structure disclosed in the Japanese Unexamined Patent Publication No. Hei 9-213839, FIG. 3B is a sectional view thereof. As shown in FIGS. 3A and 3B, in the second conventional semiconductor device 150 having the BGA structure, there is provided a semiconductor chip 151. Above the semiconductor chip 151, internal leads 155 of the plurality of the connection leads are arranged in parallel with the upper surface of the semiconductor chip 151. The semiconductor chip 151 and the internal leads 155 of the connection leads are stuck and fixed with the sticking tape 152 comprising the insulator. Furthermore, the plurality of pads 153 formed on the upper surface of the semiconductor chip 151 and the internal leads 155 of the connection leads are electrically connected with wires 154.
Furthermore, the semiconductor chip 151, the sticking tape 152, the internal leads 155 of the connection leads, the pads 153 and the wires 154 are covered with an upper package member 156 comprising a sealed resin and a lower package member 157 so that the resin sealed part is formed. At positions of the surface on the side of the internal leads of the lower package member 157 which position leads to the internal lead 155, small orifices are provided. Within the small orifices, a plurality of solder balls 158 are embedded in such a manner that each head part thereof is extended from the surface of the lower package member 157 as an external part connection terminal. This solder ball 158 is electrically connected to the internal lead 155.
In the second conventional semiconductor device 150 having the BGA structure which is constituted in this manner, in the same manner as the first conventional semiconductor device 110 having the BGA structure, by means of the reflow method for allowing the solder balls 158 to come into contact with predetermined positions of the printed wiring board 169 and heating or pressing the solder ball 158 to melt, the semiconductor device is fixed to a predetermined position of the printed wiring board 169, and at the same time, the semiconductor device is electrically connected and is attached on the printed wiring board 169.
However, as has been described above, in the first conventional semiconductor device 110 having the BGA structure and the second conventional semiconductor device having the BGA structure 150, the solder balls are embedded in the resin sealed part. As a result, an impact is propagated to the resin sealed part via the solder balls without an alleviation of the impact which is propagated from the printed wiring board at the time of the fall impact test and the temperature cycle test, which are performed in a state in which the solder balls are attached on the printed wiring board. Since the impact is applied from the resin sealed part as a the reaction force, there is a problem that a crack is generated on a bond surface with the printed wiring board in the solder ball and on a bond surface of the resin sealed part.